Method of controlling dishwasher

ABSTRACT

A method of controlling a dishwasher including washing dishes using washing water in which a detergent is dissolved, draining the washing water in which the detergent is dissolved, first rinsing the dishes using washing water in which no detergent is dissolved, and second rinsing the dishes using washing water in which a descaling agent is dissolved. The dishwasher includes a tub which accommodates the dishes, and a sump which receives the washing water supplied into the tub, and the descaling agent is input during a process of supplying the washing water from the outside of the tub to the sump.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2014-0092098, filed on Jul. 21, 2014, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

The present disclosure relates to a method of controlling a dishwasher, and more particularly, to a method of controlling a dishwasher which optimizes a point in time at which a descaling agent is supplied.

2. Background

Hard water is generally defined as washing water having hardness of 60 ppm or more, and when the hard water is heated, scale is inevitably formed. Since most of the dishwashers perform a process of heating the washing water, there may be various problems due to the scale when hard water is not appropriately processed.

An appropriate amount of descaling agent needs to be supplied in accordance with the hardness of the washing water in order to remove the scale, but because a significant amount of formed scale is discharged from the dishwasher together with drained water, the amount of descaling agent is actually required is very small.

The required amount of a descaling agent needs to be accurately input because there may occur a problem with product reliability when an excessive amount of descaling agent is supplied, and performance in removing scale may deteriorate when a insufficient amount of a descaling agent is supplied. However, it is difficult and very inconvenient for a user to accurately measure a required amount of the descaling agent.

SUMMARY

The present disclosure has been made in an effort to provide a method of controlling a dishwasher, which optimizes a point in time at which a descaling agent is supplied.

The present disclosure has also been made in an effort to provide a method of controlling a dishwasher, which may ensure sufficient descaling performance and minimize an input amount of the descaling agent.

The present disclosure has also been made in an effort to provide a method of controlling a dishwasher, which minimizes scale components contained in washing water remaining in a tub when a rinsing process is completed, and as a result, there is no contamination caused by scale even though all of the remaining washing water is removed by natural drying or the drying process.

An exemplary embodiment of the present invention provides a method of controlling a dishwasher, the method including washing dishes using washing water in which a detergent is dissolved; draining the washing water in which detergent is dissolved; rinsing the dishes using washing water in which no detergent is dissolved; and rinsing the dishes using washing water in which a descaling agent is dissolved.

The washing of the dishes using the washing water in which detergent is dissolved may include heating the washing water.

The rinsing of the dishes using the washing water in which descaling agent is dissolved may be performed after draining the washing water in which no detergent is dissolved.

The rinsing of the dishes using the washing water in which no detergent is dissolved may include rinsing the dishes using washing water in which a rinse is dissolved.

The descaling agent may include organic acid. The organic acid may be citric acid.

The constant amount of descaling agent may be input each time.

The dishwasher may include a tub which accommodates the dishes and a sump which receives the washing water supplied into the tub, in which the descaling agent is input during a process of supplying the washing water from the outside of the tub to the sump.

The method may further include drying the dishes after the rinsing of the dishes using the washing water in which descaling agent is dissolved.

The rinsing of the dishes using the washing water in which no detergent is dissolved may include heating the washing water.

The method of controlling a dishwasher may further include: prewashing the dishes using the washing water in which no detergent is dissolved; and draining the washing water that is used in the prewashing of the dishes, in which the washing of the dishes using the washing water in which detergent is dissolved is performed after the washing water used in the prewashing process is drained.

The rinsing of the dishes using the washing water in which descaling agent is dissolved may be performed as a final step of a rinsing process.

Another exemplary embodiment of the present invention provides a method of controlling a dishwasher, the method including washing dishes by applying a detergent; performing a rinsing process in which the detergent used to wash the dishes is removed with washing water; and draining the washing water used to rinse the dishes, and thereafter, rinsing the dishes by supplying washing water with descaling agent.

The performing of the rinsing process in which detergent used to wash the dishes is removed may include spraying high-temperature washing water heated by a heater onto the dishes.

The performing of the rinsing process in which the detergent used to wash the dishes is removed may include spraying the washing water, in which a rinse is dissolved, onto the dishes.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:

FIG. 1 is a perspective view of a dishwasher according to an exemplary embodiment of the present invention;

FIG. 2 is a view illustrating the dishwasher in a state in which a door is opened;

FIG. 3 is a view illustrating main components in the dishwasher;

FIG. 4 is a view schematically illustrating a descaling solution supply device;

FIG. 5 is a graph illustrating a scaling rate with respect to a pH of raw water;

FIG. 6 is a graph illustrating a relationship between the pH and the scaling rate when a temperature varies in accordance with a detergent concentration and a rinse concentration;

FIG. 7 is a graph illustrating a scaling rate according to a temperature of the raw water with respect to the amount of supplied citric acid;

FIG. 8 is a graph illustrating a scaling rate with respect to a concentration of the citric acid when a rinse is input; and

FIG. 9 is a graph illustrating a scaling rate with respect to a concentration of the citric acid when a detergent is input.

DETAILED DESCRIPTION

Advantages, features, and methods for achieving those of embodiments may become apparent upon referring to embodiments described later in detail together with the attached drawings. However, embodiments are not limited to the embodiments disclosed hereinafter, but may be embodied in different modes. The same reference numbers may refer to the same elements throughout the specification.

FIG. 1 is a perspective view of a dishwasher according to an exemplary embodiment of the present invention. FIG. 2 is a view illustrating the dishwasher in a state in which a door is opened. FIG. 3 is a view illustrating main components in the dishwasher. FIG. 4 is a view schematically illustrating a descaling solution supply device. Referring to FIGS. 1 to 4, a dishwasher according to an exemplary embodiment of the present invention includes a casing 3 which defines an external appearance, a tub 6 which is disposed in casing 3 and defines a washing space in which dishes are washed, a sump 20 in which washing water for washing the dishes is collected, and a descaling solution supply device 100 which discharges a descaling agent into the washing water supplied to sump 20. The descaling agent is discharged by dissolving in the washing water, and hereinafter, the descaling agent is defined as a material that bonds with metal ions (e.g., Ca²⁺, Mg²⁺) in hard water and inhibits formation of scale or removes formed scale, and a solution in which the descaling agent is dissolved is defined as a descaling solution.

Descaling agent ‘d’ (see FIG. 4) includes acid compositions, for example, chemicals such as organic acid including hydrochloric acid, citric acid, malic acid, tartaric acid, acetic acid, lactic acid, and formic acid, phosphoric acid, and sulfamic acid which react with alkaline carbonate and the like in the scale. The chemicals in a liquid phase as well as in a solid phase such as powder or particles may be accommodated in the descaling solution supply device. Particularly, the organic acid such as the citric acid is an environmentally-friendly material harmless to humans.

Casing 3 may include a cabinet 1 having a dish entrance opening, and a door 2 for opening and closing the dish entrance opening. A handle 2 a, a control panel 5 for controlling an operation of the dishwasher, and a display 4 for displaying an operating state of the dishwasher may be provided on door 2.

In tub 6, there are provided racks 7 a and 7 b on which the dishes are placed, and nozzles 8 a, 8 b, and 8 c which are supplied with the washing water from sump 20 and spray the washing water onto the dishes placed on racks 7 a and 7 b.

The number of racks 7 a and 7 b may be more than one. In the present exemplary embodiment, an upper rack 7 a is disposed, and a lower rack 7 b is disposed below upper rack 7 a. Additionally, the number of nozzles 8 a, 8 b, and 8 c may be more than one so that the washing water is sprayed in various directions, and nozzles 8 a, 8 b, and 8 c may include an upper nozzle 8 a which sprays the washing water downward toward upper rack 7 a, an intermediate nozzle 8 b which is disposed between upper rack 7 a and lower rack 7 b and sprays the washing water downward toward lower rack 7 b, and a lower nozzle 8 c which is disposed below lower rack 7 b and sprays the washing water upward. Although not illustrated, guide flow paths, which guide the washing water from sump 20 to the respective nozzles, may be provided corresponding to the configurations of the nozzles, and a flow path switching unit (not illustrated), which selectively intermits the guide flow paths, may be further provided. There may be further provided a washing pump 40 which pumps the washing water received in sump 20 to the guide flow path, and heater 52 which heats the washing water in sump 20.

The dishwasher may include a water supply device 30 which supplies the washing water to sump 20. Water supply device 30 may be disposed between tub 6 and cabinet 1. Water supply device 30 may include flow paths which guide a flow of the washing water, water chambers which receive the washing water guided by the flow paths, a water supply hose connector 32 a which is connected with a water supply hose into which raw water (e.g., tap water) flows, a flowmeter 33 which detects the amount of raw water flowing into the water supply hose connector 32 a, a water chamber 31 which stores the washing water flowing therein, and a vent opening (not illustrated) which communicates the flow paths with the atmosphere in order to prevent siphonage in which the raw water consistently flows in even though water supply is shut off.

According to exemplary embodiments, in addition to the flow path that supplies the washing water to sump 20, water supply device 30 may further include a flow path which allows the washing water to be supplied directly to tub 6 without passing through sump 20.

Water supply device 30 may further include a sump drain connector 32 c which is connected with a sump drain flow path (not illustrated) along which the washing water used to wash the dishes is guided and drained from sump 20, and a drain pump inlet connector 32 d which is connected with a drain pump inlet flow path (not illustrated) that guides the washing water flowing into the drain pump.

Washing pump 40 may include a washing water guide 41 which guides the washing water in sump 20 to nozzles 8 a, 8 b, and 8 c, an impeller 42 which is rotatably provided in washing water guide 41, and a washing motor 43 which rotates impeller 42.

Water supply valve 113 controls the supply of the washing water to sump 20, and may be provided to intermit the discharge of the washing water from water supply device 30 in a case in which water supply device 30 is configured to supply the washing water to sump 20. Otherwise, in a case in which the washing water is supplied directly to sump 20 from an external water source, water supply valve 113 may be provided to intermit the supply of washing water from the external water source. Operations of water supply valve 113, washing motor 43 and the like are controlled by a controller (not illustrated).

Sump 20 and tub 6 are in communication with each other, such that the washing water sprayed by nozzles 8 a, 8 b, and 8 c flows back into sump 20 from tub 6. Furthermore, tub 6 is also in communication with a washing water outlet 112 h of descaling solution supply device 100, which will be described below, through sump 20, and as a result, water pressure applied in washing water outlet 112 h varies according to a water level in tub 6.

A filter 51 may be further provided in sump 20, and in this case, the washing water, which has been sprayed into tub 6 through nozzles 8 a, 8 b, and 8 c, is filtered while passing through filter 51, and then flows back into sump 20.

In addition, the dishwasher may include an additive inputting mechanism (not illustrated) which inputs a detergent or a rinse into the washing water, and the additive inputting mechanism inputs the detergent for washing the dishes or the rinse for rinsing the dishes into tub 6 at a predetermined step during a washing process or a rinsing process.

FIG. 4 is a view schematically illustrating a descaling solution supply device. Descaling solution supply device 100 is a device that supplies a descaling agent into the washing water. Descaling solution supply device 100, which will be described below, discharges a descaling solution to a flow route of the washing water supplied to sump 20, but the present invention is not necessarily limited thereto, and the descaling agent may be supplied in any phase such as the form of powder or particles in accordance with exemplary embodiments.

Referring to FIG. 4, descaling solution supply device 100 includes a solution accommodating unit 111 which accommodates the descaling agent, a main flow path 112 which guides the washing water to sump 20 during a process of supplying the washing water so that the washing water bypasses solution accommodating unit 111, and a branch flow path 120 which branches off from main flow path 112 and guides the washing water, which is guided along main flow path 112, to solution accommodating unit 111.

Main flow path 112 may be divided into an upstream side main flow path 112 a positioned at an upstream side and a downstream side main flow path 112 b positioned at a downstream side, based on a portion where main flow path 112 is connected with branch flow path 120.

The descaling agent in the form of powder or particles may be input into solution accommodating unit 111. The sufficient amount of the descaling agent may be input so that the overall amount of the inputted descaling agent is not dissolved in the washing water, but only a part of the descaling agent is dissolved, and the remaining descaling agent is present in a precipitated state. That is, the washing water in solution accommodating unit 111 is maintained in a saturated or supersaturated state for a sufficient time until the descaling agent is consumed and the washing water becomes an unsaturated state.

The duration at which a solution discharge valve 130 is opened to supply the descaling agent each time may be set so that the descaling solution may be input roughly 4,000 to 5,000 times until the washing water in solution accommodating unit 111 becomes an unsaturated state.

Solution accommodating unit 111 has a solution outlet 111 h through which the descaling solution produced in solution accommodating unit 111 is discharged. Solution discharge valve 130 may be further provided to open and close solution outlet 111 h. Solution outlet 111 h is maintained in a closed state by solution discharge valve 130 during the process of supplying the washing water. Solution discharge valve 130 may be a solenoid valve that is operated by being controlled by the controller.

Branch flow path 120 includes an atmosphere communicating port 123 which is positioned above solution outlet 111 h and communicates with the atmosphere. Atmosphere communicating port 123 may communicate with the atmosphere even while the washing water is supplied into solution accommodating unit 111. Because atmospheric pressure is applied through atmosphere communicating port 123, the water head is constantly maintained at a downstream side branch flow path 122 of atmosphere communicating port 123 on branch flow path 120 even though the supply of the washing water is shut off in a state in which solution accommodating unit 111 is filled with the washing water. Particularly, since the supply of washing water to sump 20 is carried out in a state in which solution outlet 111 h is closed, and a substantially constant atmospheric pressure is applied to atmosphere communicating port 123, the washing water in branch flow path 120 maintains a constant head difference with respect to solution outlet 111 h when the supply of the washing water is shut off, and as a result, the descaling solution may be quantitatively discharged from solution accommodating unit 111 when solution discharge valve 130 is opened. Particularly, because a water level in branch flow path 120 is constantly maintained with respect to solution outlet 111 h, the descaling solution may be quantitatively discharged through solution outlet 111 h even though water supply pressure varies in accordance with characteristics of locations where the dishwasher is used.

Meanwhile, when solution accommodating unit 111 is filled with the washing water supplied through branch flow path 120 in a state in which solution outlet 111 h is closed by solution discharge valve 130, the washing water does not flow into solution accommodating unit 111 anymore, but flows into water supply device 30 through atmosphere communicating port 123. Thereafter, when the supply of the washing water is shut off, the amount of washing water which exceeds a maximum water level H in downstream side branch flow path 122 and the amount of washing water remaining in upstream side branch flow path 121, of the overall amount of washing water in branch flow path 123, are moved downward by self-weight and flow into sump 20 along main flow path 112.

When the supply of the washing water is shut off in a state in which solution accommodating unit 111 is filled with the washing water, water level H in downstream side branch flow path 122 is constantly set, and the water level maintains a constant head difference ΔH with respect to solution outlet 111 h, such that the water level is defined as a head difference maintaining water level H. The water level in tub 6 may be maintained to be the head difference maintaining water level H or lower. The reason is that the descaling solution needs to be discharged from solution accommodating unit 111 by the head difference ΔH when solution discharge valve 130 is opened.

A water level detecting sensor (not illustrated), which detects the water level in tub 6, may be further provided. When a predetermined condition is satisfied, that is, when the water level detected by the water level detecting sensor reaches a predetermined water level or when the amount of supplied washing water detected by flowmeter 33 reaches a predetermined amount, the controller controls and closes water supply valve 113. Thereafter, the controller opens solution discharge valve 130 at a predetermined point of time so that the descaling solution is discharged to main flow path 112 b from solution accommodating unit 111, and thereafter, the controller opens water supply valve 113 again so that the washing water flows along main flow path 112 b and then is supplied to sump 20 together with the descaling solution. In order to quantitatively supply the descaling solution, the operation of opening solution discharge valve 130 may be controlled based on time. That is, the duration at which solution discharge valve 130 is opened is constantly controlled, such that the amount of descaling solution, which is supplied through descaling solution supply device 100 each time, may be constantly controlled.

Meanwhile, in the exemplary embodiment, branch flow path 120 has atmosphere communicating port 123 formed at the uppermost end of the flow path, and based on atmosphere communicating port 123, upstream side branch flow path 121 guides the washing water upward, and downstream side branch flow path 122 guides the washing water downward, but the present invention is not necessarily limited thereto. The position of atmosphere communicating port 123 may be changed as necessary within a range in which the water level in downstream side branch flow path 122 maintains a constant head difference with respect to solution outlet 111 h.

In general, the dishwasher performs a washing process and a rinsing process. The washing process serves to remove contaminants attached to the dishes, and the detergent for washing the dishes may be input during the process. Hereinafter, the washing water in which the detergent is dissolved is referred to as detergent water. The washing process may be configured as a single process in which water supply and water drainage are carried out once, but the water supply and the water drainage may be carried out several times in accordance with exemplary embodiments. The washing process may include a prewashing process which is carried out one or more times, and a main washing process which is carried out after the prewashing process. The prewashing process is a step of roughly removing contaminants attached to the dishes in advance prior to the main washing process, and the washing water without detergent (hereinafter, referred to as raw water) is sprayed onto the dishes. The prewashing process may be carried out several times in order to sufficiently remove and soak the contaminants, water drainage is carried out after the respective prewashing processes, and then the next prewashing process or the main washing process may be carried out. At the time of the main washing process, the detergent water may be sprayed through nozzles 8 a, 8 b, and 8 c, and the detergent water may be heated by heater 52 and then sprayed.

The rinsing process is a process of rinsing the dishes, and is mainly carried out after the washing process, but a menu, which allows a user to select only the rinsing process separately, is sometimes provided in accordance with exemplary embodiments. In the rinsing process, the detergent is not input, and the washing water supplied from the external water source is used as it is, or the washing water (hereinafter, referred to as rinse water), which is mixed with the rinse for rinsing the dishes, may be used. For example, the rinsing process may include at least one normal rinsing process, and a heating and rinsing process that is carried out after the normal rinsing process. At the time of the normal rinsing process, the raw water or the rinse water, which is not heated, is sprayed onto the dishes, and at the time of the heating and rinsing process, the raw water or the rinse water, which is heated by heater 52, is sprayed onto the dishes.

A method of controlling the dishwasher according to the exemplary embodiment of the present invention includes washing the dishes using the washing water (detergent water) in which the detergent is dissolved, draining the washing water in which the detergent is dissolved, rinsing the dishes using the washing water (raw water or rinse water) in which no detergent is dissolved, and rinsing the dishes using the washing water in which the descaling agent is dissolved.

FIG. 5 is a graph illustrating a scaling rate with respect to a pH of the raw water. FIG. 6 is a graph illustrating a relationship between the pH and the scaling rate when a temperature varies in accordance with a detergent concentration and a rinse concentration. FIG. 7 is a graph illustrating a scaling rate according to a temperature of the raw water with respect to the amount of supplied citric acid. FIG. 8 is a graph illustrating a scaling rate with respect to a concentration of the citric acid when the rinse is input. FIG. 9 is a graph illustrating a scaling rate with respect to a concentration of the citric acid when the detergent is input.

Referring to FIG. 5, the amount of scale is increased as the pH of the washing water becomes higher. Hereinafter, when a predetermined amount of hard water (hereinafter, hardness is 300 ppm, for example) is left unattended at a predetermined temperature and a predetermined pH for a predetermined time (hereinafter, referred to as a Comparative Example), the scaling rate refers to a rate of the amount of scale formed during respective experiments with respect to the amount of formed scale (hereinafter, referred to as a referent amount). For example, FIG. 5 is a graph illustrating a variation in the scaling rate with respect to a pH condition of the washing water, in a case in which the dishes are washed by spraying the same amount of washing water (hardness is 300 ppm) as the Comparative Example onto the dishes for a predetermined time. In FIG. 5, the pH of the washing water is adjusted by the input amounts of hydrochloric acid (HCl) and sodium hydroxide (NaOH). It can be seen from FIG. 5 that the formation of scale is inhibited in a case in which the washing water is acidic, but a large amount of scale is formed as a pH value is increased, that is, when the washing water becomes more basic, for example, at a pH of 8 to 9 or higher.

Particularly, the detergent helps to increase the pH value of the washing water, and a large amount of scale is formed at the time of the main washing process in which the dishes are washed by using the detergent water. On the contrary, the rinse helps to decrease the pH of the washing water, and the formation of scale is inhibited at the time of the normal rinsing process in which the dishes are rinsed by using the rinse water.

Effects of the detergent and the rinse on the formation of scale can be seen from FIG. 6. In FIG. 6, in a case in which a reference amount of rinse (rinse (×1) concentrated one time) is input, the pH of the rinse water is about 7.4, and in the case of the rinse concentrated five times (rinse (×5)), the pH is about 6.2. It can be seen from the drawings that even though the scaling rate has a tendency to be increased as the temperature of the washing water is increased, the scaling rate in the case of the rinse water is lower than the scaling rate in the case of the detergent water or the raw water at the same temperature. That is, it is presumed that the rinse serves to inhibit the formation of scale or remove the formed scale, and as a result, the descaling agent is not input before the normal rinsing process, but instead the descaling agent may be input after the descaling function by the rinse is carried out by performing the normal rinsing process. In this case, because the descaling action by the rinse is carried out in advance, it is possible to ensure sufficient descaling performance even though a tiny amount of descaling agent is input.

Additionally, the rinse has an effect in that the scaling rate is decreased by the rinse itself or an interaction with the descaling agent. Referring to FIG. 8, it can be seen that the scaling rate is low in a case in which the rinse is input into the washing water in comparison with a case in which the rinse is not input, and particularly, the scaling rate is decreased as a concentration of the citric acid supplied as the descaling agent is increased. Therefore, the descaling agent may be supplied at a step of inputting the rinse during the rinsing process, and for example, the descaling agent may be input together with the rinse at the time of the normal rinsing process, or the unheated raw water and the rinse may be supplied together after the heating and rinsing process. However, in the case of the latter, since an additional rinse needs to be carried out so that a remnant of the rinse does not remain on the dishes, the rinsing process may be finished by a step of spraying the washing water, in which the descaling agent is dissolved in the unheated raw water, except for the rinse, and in this case, the citric acid, which is harmless to humans even though the remnant remains on the dishes after the rinsing process is completed, is suitable as the descaling agent.

FIG. 7 is a graph illustrating the scaling rate according to the variation in the temperature of the washing water while comparing a case in which the raw water with hardness of 300 ppm is used without inputting the detergent or the rinse, a case in which low-concentration citric acid is input into the raw water, and a case in which high-concentration citric acid is input into the raw water. It can be seen from the graph that first, the scaling rate is decreased as the concentration of the citric acid is increased, and second, the scaling rate is increased as the temperature of the washing water is increased.

Particularly, in order to actively remove the scale formed under a high-temperature environment, the descaling agent may be supplied together with the unheated raw water after the heating and rinsing process is completed. For example, after the heating and rinsing process, a step of spraying the descaling agent together with the washing water may be additionally carried out. After the washing water used at the time of the heating and rinsing process is drained, the raw water is supplied to the sump 20 again, and in this process, the descaling solution may be supplied through the descaling solution supply device 100.

Referring back to FIG. 6, it can be seen that the detergent input into the washing water is a factor that not only increases the pH value, but also increases the scaling rate. Particularly, referring to FIG. 9, it can be seen that in a state in which the detergent is input, even though the concentration of the citric acid supplied to the detergent water is increased, the scaling rate is not apparently decreased as long as the concentration of the citric acid does not exceed a significant value (about 1,000 ppm). Therefore, the supply of the descaling agent to the detergent water is inefficient because the descaling action is not smoothly induced in a case in which a tiny amount of descaling agent is supplied, and consumption of the descaling agent is increased in a case in which a large amount of descaling agent is supplied. Therefore, the descaling agent may not be input during a step of spraying the detergent water onto the dishes (e.g., the main washing process). Hereinafter, in the examples of courses that may be provided by the dishwasher, an appropriate timing of inputting the descaling agent will be described.

TABLE 1 Rinsing Washing Heating Main and Course Prewashing 1 Prewashing 2 Prewashing 3 Washing Normal 1 Normal 2 Rinsing Drying Quick/Drying ∘ ∘ ∘ ∘(50° C.) ∘ ∘ ∘(72° C.) ∘ Quick ∘ ∘ ∘(50° C.) ∘(50° C.) Powerful ∘ ∘ ∘(60° C.) ∘ ∘ ∘(70° C.) ∘ Delicate ∘ ∘ ∘(50° C.) ∘ ∘(68° C.) ∘ Removing ∘ Scale

Referring to Table 1, a quick/drying course includes a washing process including a first prewashing process (Prewashing 1), a second prewashing process (Prewashing 2), a third prewashing process (Prewashing 3), and a main washing process, a rinsing process including a first normal rinsing process (Normal 1), a second normal rinsing process (Normal 2), and a heating and rinsing process, and a drying process. Hereinafter, the quick/drying course will be described.

The prewashing process soaks contaminants attached to the dishes in advance in order to improve washing power during the main washing process that is carried out subsequently. After the prewashing process, the main washing process of operating heater 52 to heat the washing water and spraying the heated detergent water onto the dishes is carried out. The temperature of the detergent water at the time of the main washing process reaches about 50° C. In a case in which the main washing process is carried out by using the washing water heated by heater 52 as described above, heater 52 may not be operated during the prewashing process, but heater 52 may of course be operated even at the time of the prewashing process in accordance with exemplary embodiments.

The rinsing process of the quick/drying course includes a first normal rinsing process (Normal 1), a second normal rinsing process (Normal 2), and a heating and rinsing process. The rinse water may be sprayed onto the dishes during the first normal rinsing process and/or the second normal rinsing process, and the raw water heated by heater 52 is sprayed onto the dishes during the heating and rinsing process. Because the temperature in tub 6 is increased by the heating and rinsing process, drying efficiency in the drying process, which is carried out subsequently, is improved. The temperature of the raw water at the time of the heating and rinsing process reaches about 72° C. The dishwasher may include an air discharge duct (not illustrated) which guides discharge of air in tub 6, and an air discharge fan (not illustrated) which blows air through the air discharge duct. During the drying process, the air discharge fan is operated to consistently discharge high-temperature and humid air in tub 6 to the outside through the air discharge duct, thereby decreasing humidity in tub 6 and drying the dishes.

In the quick/drying course configured as described above, the supply of the descaling agent may be carried out during the heating and rinsing process or after the heating and rinsing process. However, the detergent, which has been input at the time of the main washing process, remains in tub 6 during the heating and rinsing process, and as a result, the descaling action may be hindered by the influence of the detergent even though the descaling agent is input. Therefore, the quick/drying course may be controlled so that the washing water used at the time of the heating and rinsing process is drained, and thereafter, the descaling agent is supplied to sump 20 together with the raw water, and the washing water is sprayed into tub 6 through nozzles 8 a, 8 b, and 8 c. After the descaling agent is supplied, the washing water is drained, and then the drying process may be carried out.

The quick washing course may include a washing process including a first prewashing process, a second prewashing process, and a main washing process, a rinsing process including a single heating and rinsing process, and a drying process. In the main washing process, the dishes are washed by the washing water heated by heater 52. After the main washing process, the washing water is drained, and the heating and rinsing process is carried out in order to remove detergent elements remaining on the dishes. In the quick washing course, the supply of the descaling agent may be carried out during the heating and rinsing process or after the heating and rinsing process like the quick/drying course, but is preferably carried out after the heating and rinsing process. The quick washing course may be controlled so that the washing water used at the time of the heating and rinsing process is drained, and thereafter, the descaling agent is supplied to sump 20 together with the raw water, and the washing water is sprayed into tub 6 through nozzles 8 a, 8 b, and 8 c. After the descaling agent is supplied, the washing water is drained, and then the drying process may be carried out.

The powerful course may include a washing process including a first prewashing process, a second prewashing process, and a main washing process, a rinsing process including a first normal rinsing process, a second normal rinsing process, and a heating and rinsing process, and a drying process. In the main washing process, the dishes are washed by the washing water heated by heater 52. The temperature of the detergent water at the time of the main washing process reaches about 60° C., and the temperature of the raw water at the time of the heating and rinsing process reaches about 70° C. In the powerful course, the supply of the descaling agent may be carried out during the heating and rinsing process or after the heating and rinsing process like the aforementioned courses, but is preferably carried out after the heating and rinsing process. After the descaling agent is supplied, the washing water is drained, and then the drying process may be carried out.

The delicate course may include a washing process including a first prewashing process, a second prewashing process, and a main washing process, a rinsing process including a first normal rinsing process, and a heating and rinsing process, and a drying process. In the main washing process, the dishes are washed by the washing water heated by heater 52. The temperature of the detergent water at the time of the main washing process reaches about 50° C., and the temperature of the raw water at the time of the heating and rinsing process reaches about 68° C. In the delicate course, the supply of the descaling agent may be carried out during the heating and rinsing process or after the heating and rinsing process like the aforementioned courses, but is preferably carried out after the heating and rinsing process. After the descaling agent is supplied, the washing water is drained, and then the drying process may be carried out.

In the aforementioned courses, the descaling agent is supplied to the raw water supplied to sump 20 after at least one rinsing process is carried out after the main washing process in which the detergent is input in order to avoid antagonism with the detergent. The rinse may be input at the time of the normal rinsing process that is carried out after the main washing process, and the descaling agent may be supplied at the time of the normal rinsing process, but in this case, the rinsing process using the raw water needs to be subsequently carried out once more after the washing water is drained in order to remove the rinse, and particularly, in a case in which the entire rinsing process is finished in a state in which the subsequent step is the heating and rinsing process, there is a problem in that scale is formed again under a high-temperature environment. Therefore, in a final step of the rinsing process, the descaling agent needs to be supplied together with the raw water, and in a case in which the heating and rinsing process is carried out, the high-temperature washing water is drained, and thereafter, the descaling agent may be supplied together with the unheated raw water. The descaling agent, which is supplied at the final step of the rinsing process as described above, remains in a tiny amount even in the washing water adsorbed to the configurations such as tub 6 or heater 52 after the washing water is drained, thereby inhibiting scale from being formed during the drying process.

The method of controlling the dishwasher according to embodiments of the present invention optimize a point of time at which the descaling agent is supplied, thereby allowing the descaling action to be smoothly carried out and minimizing consumption of the descaling agent at any one time.

Additionally, the method of controlling the dishwasher according to embodiments of the present invention minimize scale components contained in the washing water remaining in the tub when the rinsing process is completed, thereby preventing contamination caused by the scale even though all of the remaining washing water is removed by natural drying or the drying process.

Furthermore, the method of controlling the dishwasher according to embodiments of the present invention may improve the descaling performance by preventing detrimental effects caused by the detergent during a process in which the descaling agent acts. 

What is claimed is:
 1. A method of controlling a dishwasher, comprising: washing dishes using washing water in which a detergent is dissolved; draining the washing water in which the detergent is dissolved; first rinsing the dishes using washing water in which no detergent is dissolved; and second rinsing the dishes using washing water in which a descaling agent is dissolved.
 2. The method of claim 1, wherein the washing of the dishes includes heating the washing water.
 3. The method of claim 1, wherein the second rinsing of the dishes is performed after draining the washing water in which no detergent is dissolved.
 4. The method of claim 1, wherein the first rinsing of the dishes includes rinsing the dishes using washing water in which a rinse is dissolved.
 5. The method of claim 1, wherein the descaling agent includes an organic acid.
 6. The method of claim 5, wherein the organic acid is citric acid.
 7. The method of claim 1, wherein a constant amount of the descaling agent is input to be dissolved each time the descaling rinse is performed.
 8. The method of claim 1, wherein the dishwasher includes a tub which accommodates the dishes, and a sump which receives the washing water supplied into the tub, and the descaling agent is input during a process of supplying the washing water from the outside of the tub to the sump.
 9. The method of claim 1, further comprising: drying the dishes after the second rinsing of the dishes.
 10. The method of claim 1, wherein the first rinsing of the dishes includes heating the washing water.
 11. The method of claim 1, further comprising: prewashing the dishes using the washing water in which no detergent is dissolved; and draining the washing water that is used in the prewashing of the dishes, wherein the washing of the dishes is performed after the washing water used in the prewashing process is drained.
 12. The method of claim 1, wherein the second rinsing of the dishes is performed as a final step of a rinsing process.
 13. A method of controlling a dishwasher, comprising: washing dishes by applying a detergent; performing a rinsing process in which the detergent used to wash the dishes is removed with washing water; and draining the washing water used to rinse the dishes, and thereafter, performing a descaling process in which the dishes are rinsed by supplying washing water with descaling agent.
 14. The method of claim 13, wherein the performing of the rinsing process includes spraying high-temperature washing water heated by a heater onto the dishes.
 15. The method of claim 13, wherein the performing of the rinsing process includes spraying washing water, in which a rinse is dissolved, onto the dishes. 